The present invention relates to a metal laminate gasket having sealing portions with different surface pressures for sealing around a hole.
In an internal combustion engine, in order to provide a light engine, a cylinder block as well as a cylinder head may be made of an aluminum alloy. In this case, if high surface pressure is applied through a gasket to seal around a cylinder bore at a portion immediately outside the cylinder bore, the cylinder bore may deform by the high surface pressure.
Even if a cylinder liner is installed in the cylinder block to define the cylinder bore, in case a high surface pressure is applied to the cylinder liner to seal around the cylinder bore, the cylinder liner may deform.
In Japanese Utility Model Publication No. 63-82056, a gasket includes a first sealing portion around a cylinder bore, which is formed by turning a plate around the cylinder bore, and a bead outside the first sealing portion to resiliently seal therearound. In this case, a high surface pressure is formed immediately outside the cylinder bore to securely seal around the cylinder bore, and the bead secondarily seal around the cylinder bore. Thus, the cylinder bore or the cylinder liner may deform.
In order to solve the above problem, U.S. Pat. No. 4,739,999 has been proposed to provide auxiliary and main sealing devices around a hole to be sealed. The auxiliary sealing device located close to the hole to be sealed provides sealing pressure less than that of the main sealing device to thereby prevent deformation of the cylinder liner.
The above U.S. patent operates as intended. However, the gasket of the above patent resiliently seals around the cylinder bore. In case resiliency is not required, or the cylinder head does not have strong rigidity, the gasket as disclosed in the above U.S. patent is not used.
Accordingly, one object of the invention is to provide a metal laminate gasket, wherein deformation of a cylinder block around a cylinder bore or a cylinder liner is prevented.
Another object of the invention is to provide a metal laminate gasket as stated above, wherein the cylinder bore can be securely sealed therearound.
A further object of the invention is to provide a metal laminate gasket as stated above, wherein even if rigidity of the cylinder head is not strong, vibration or deformation of the cylinder head is substantially prevented.
A still further object of the invention is to provide a metal laminate gasket as stated above, wherein the gasket can be easily and economically manufactured.
Further objects and advantages of the invention will be apparent from the following description of the invention.